Fatty Acid Content in Biomasses: State-Of-The-Art and Novel Physical Property Estimation Methods

Hindawi International Journal of Chemical Engineering Volume 2019, Article ID 2430234, 25 pages https://doi.org/10.1155/2019/2430234 Research Article Fatty Acid Content in Biomasses: State-of-the-Art and Novel Physical Property Estimation Methods Ana M. Sousa ,1 Thalles A. Andrade ,2 Massimiliano Errico ,2 Jose´ P. Coelho ,3,4 Rui M. Filipe ,1,3 and Henrique A. Matos 1 1CERENA/DEQ, Instituto Superior Tećnico, Universidade de Lisboa, Av. Rovisco Pais 1, Lisboa, Portugal 2Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark 3Instituto Superior de Engenharia de Lisboa, Instituto Politećnico de Lisboa, 1959-007 Lisboa, Portugal 4CQE, Instituto Superior Tećnico, Universidade de Lisboa, Av. Rovisco Pais 1, Lisboa, Portugal Correspondence should be addressed to Massimiliano Errico; [email protected] Received 14 June 2019; Accepted 22 September 2019; Published 23 November 2019 Academic Editor: Maurizio Volpe Copyright © 2019 Ana M. Sousa et al. (is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In line with the growing environmental awareness developed along the last decades, modern societies are urged to evolve into sustainable economics where the reuse of organic wastes represents the key feedstock for a green transaction. (e oil phase obtained from different biomasses has the potential to be a source of food supplements, medicines, cosmetics, or feedstock for biofuel production. In the present work, the composition of 104 different biomasses including seeds, peels, flowers, plants, and leaves has been reviewed for the lipid content. Based on the most frequent fatty acids screened, experimental data for normal boiling point temperature, normal melting point, critical properties, and acentric factor were collected and compared with the most common estimation methods, which are functions of the molecular structure and interaction between different functional groups. New predictive equations have been proposed to reduce the estimation deviation and to provide simple correlations to be used in simulation software when dealing with biomass processes. For all the properties, the estimations proposed have an absolute average deviation equal to or lower than 4.6%. 1. Introduction with the chemical industry and petroleum exploration [2], incorporated in the broader research initiative aiming to (e development of sustainable processes can be pursued develop integrated processes and product design for sus- through multiple paths, among which decreasing wastes, tainable biorefineries [3]. increasing efficiency in industrial processes, mitigating en- Fatty acids are long hydrocarbon chains with a terminal vironmental and human risks, reducing pollutant agents, carboxyl group. (ey can be obtained from rather abundant and fostering energy production from renewable sources organic compounds, including organic matter wastes [4, 5] play unquestionable roles. or nonedible oils [6, 7]. Fatty acids are characterized by an Within this context, biomass appears as a valuable outstanding range of applications within the energy domain, feedstock to recover several compounds and/or produce such as biofuels [8], and flow improvers for crude oils [9–12], energy to answer the global consumption growth without or within other high end industries such as food supple- creating a negative legacy to the next generations [1]. In fact, ments [13], cosmetics [14], medicines, and drugs [15, 16]. the widespread employment of biomass not only bears the Fatty acids, often referred to as fats, are used in the potential of recovering industrial wastes as a valuable resource human body to store excess energy, and they constitute the but also leverages the energy and industrial productions building blocks for membrane cells [17, 18]. Moreover, as through efficient and less polluting engineering processes. recommended by the Food and Agriculture Organization of (is work is deemed to study the potential of fatty acids the United Nations [19], there is convincing evidence that in addressing significant multidisciplinary issues associated some fatty acids like the linoleic acid and the alpha-linoleic 2 International Journal of Chemical Engineering acid are indispensable for human health even if they cannot centrally, for the production of valuable final products or be synthesized. intermediates with applications in pharmaceutical, food and Considering the broad range of fatty acid applications, beverages, or even nutraceutical fields [21]. Subsequently, an extensive review of their amount and composition in waste biomass effluents could be treated to produce lower different biomasses has been drawn. added-value products, e.g., insecticides or pesticides, or used Such remarkable potential opens the definition of new as feedstock for biofuel production. industrial processes for fatty acid recovery from different A total of 104 different types of oils obtained by ex- biomasses contributing to valorize poor feedstocks and to traction of different biomasses were collected from the reduce their environmental impact when treated as wastes. scientific literature to identify the most common and Such approach paved the way in applying strategies deemed frequent fatty acids. (e list of oil sources and main fatty to foster sustainability on an industrial scale. acid composition is reviewed in Table 1. (e information Within a biorefinery approach, the target compounds are was collected and summarized from different published recovered or obtained from the biomass through a series of works, and when available, the minimum and maximum processes classified as thermochemical, biochemical, me- concentration values were reported. In some cases, the chanical/physical, and chemical [20]. It means that, in order to percentage of oil content in the biomass matrix was also move from the definition of the biomass potential in re- included. (is value could be useful to determine a possible covering or obtaining some compounds to the process setup, a upper bound oil extraction yield from the biomass matrix. reliable model must be available to design the single unit In Table 1, 16 fatty acids were listed since, according to the operation and to define the process global performance and sources reviewed, they appear in the oil in a significant profitability. Product and process design rely on the knowledge amount. of the properties of chemical compounds and their mixtures. Ricinoleic acid, lesquerolic acid, and elaeostearate acid, Although large databases of experimental data are available, the main constituents of castor oil, lesquerella oil, and tung covering the complete set of compounds, mixtures, and op- oil, respectively, were not reported since they do not appear erating conditions is a huge task that may not be economically in the other biomasses listed. Information about their feasible. Property estimation models for physical properties are quantity is provided in Table 1 notes. widely used when experimental data are not available. Figure 1 shows the average of each fatty acid yield in the Unlike what can be found in published research con- biomasses and their frequency of appearance. cerning thermophysical properties of pure compounds, this (e fatty acid yield average was obtained by considering work has been focused on the most important temperature- the values reported in Table 1. For those cases where a yield independent physical properties of the main fatty acids interval is indicated, the average was calculated. (e fre- found in biomass feedstocks. (ese properties are also es- quency of appearance expresses the occurrence of fatty acid sential in improving the processes modeling, in the for- in the set of biomasses. mulation of product portfolios and for the composition Regarding the saturated fatty acids, palmitic acid (C16 : 0) assessment of the generated pollutants. and stearic acid (C18 : 0) are the ones with the highest content Published prediction methods were critically analyzed and frequency in all the bio-oils examined. Considering given the scarcity of experimental data for determining the the unsaturated fatty acids, oleic acid (C18 :1), linoleic acid relevant physical properties. Considering current methods (C18 : 2), and linolenic acid (C18 : 3) are the most plentiful shortcomings for the intended applications and using the compounds identified in the reported bio-oils. However, National Institute of Standards and Technology (NIST) since the average yield reported in Figure 1 was evaluated database as a reference, innovative estimation methods were considering the distribution of the single fatty acids, a more developed. Such correlation’s novelty is not only limited to a revealing indicator is the average minimum and average higher accuracy but also finds a significant advantage in its maximum, reported in Figure 2 as a grey rectangle. (e simplicity, given the use of molecular weight (MW) and the minimum and maximum averages were published together maximum number of double bonds (DBs) in the molecule as with the absolute minimum and absolute maximum. On the input. To sum up, a reliable method for the estimation of one hand, taking caprylic acid as an example, its average yield fatty acid (FA) physical properties was developed. (erefore, range is from 0.2% to 5.2%, which is a very narrow range, a set of six new correlations have been proposed to reduce

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